| Summary: | 博士 === 國立交通大學 === 機械工程系所 === 104 === The present study established four Savonius wind rotors into a parallel system, installed at a rural open field in Zhubei city of HsinChu County, to generate electric power by using the wind power. Meanwhile, a solar panel, which can generate power by solar energy, was set up in front of the bottom of the parallel system to guide the air flow impinging on the rotors. The solar panel is inclined 23° from the horizon. This dissertation is separated into two parts. First, a computational fluid dynamics (CFD) software, Fluent, was used to analyze the flow fields and the system performance, including the best overlap ratio of one single Savonius wind rotor, performance of four Savonius wind rotors in parallel system and optimal spacing of the parallel system with solar panel deflector. Then, experiments were carried under the various wind velocities and rotational speeds of wind rotors to deduce the relationship between tip-speed ratio (TSR) and power coefficient (Cp). The analyses for the results of numerical simulations experiments are discussed in detail and, finally, a comparison is given.
For the numerical simulate results, the optimal performance is found to occur at overlap ratio equal to 0.15, which is adopted for all parametric studies, and the addition of solar panel deflector to parallel system can enhance the performance as expected. The maximum Cp value of parallel system without deflector is 0.289 at TSR 0.8, whereas such value is 0.389 at TSR 0.8 under the best spacing of 50 cm between the parallel system and deflector. The augment of Cp is 1.34 times. From velocity vector distribution, it can be seen that the deflector can guide the underneath air flow to impinge on the rotors to gain an extra wind power.
On the other hand, the experimental results show that the wind velocity and rotational speed of wind rotors have large fluctuation in open field. Therefore, the present study repeated the experiments in day and night for different seasons to measure Cp and TSR. The measured average wind speed is 6.99±1.52 m/s with a coefficient of variation of 21.7% in plant. The four Savonius wind rotors in parallel system can generate 8.25 kWh per day, whose optimum power generation efficiency is 20.7%. The 3kW wind and solar hybrid integration system, which applies the best simulation conditions to the design of experiment, can generate power of 14.55 kW∙hr per day that can sufficiently provide power usages for three general families in winter, and the corresponding optimum power generation efficiency is 21.7%. From the result of Cp curve, it can find that the deflector indeed can improve the system performance up to 10.1%.
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